Secondary cell

Abstract

Provided is a secondary cell which is resistant to vibration and impact. The secondary cell includes a flat wound group supported, through an insulator, at a lid on which external terminals are arranged, and a cell case for housing the flat wound group. In the secondary cell, a flat portion of the flat wound group has a gap between the flat portion and a wide surface of the cell case, and is held on the wide surface near a cell case bottom through a holding portion.

The invention claimed is: 
     
       1. A secondary cell comprising:
 a flat wound group including a flat portion and a curved portion; 
 a cell case; and 
 a case lid that is configured to seal the cell case, wherein
 the flat wound group comprises an active material mixture applied portion and an insulating sheet insulating the flat wound group and the cell case from each other, and is housed in the cell case, 
 the case lid supports the flat wound group on one end side of the flat wound group, 
 a gap is formed between the curved portion and the cell case, 
 the insulating sheet is formed by plurality of superposed insulating layers including at least an outside wide layer and an inside wide layer on the flat portion, 
 the flat wound group is connected to the case lid through positive and negative current collectors, and 
 the inside wide layer is formed of: i) a hole constituting a gap between the flat portion and the outside wide layer, and ii) a portion that is configured as a holding portion for the flat wound group between the flat portion on the other end side of the flat wound group and the outside wide layer. 
 
 
     
     
       2. The secondary cell according to  claim 1 , wherein
 the holding portion is provided on both sides of the flat wound group. 
 
     
     
       3. The secondary cell according to  claim 1 , wherein
 the holding portion is provided between the cell case and the active material mixture applied portion. 
 
     
     
       4. The secondary cell according to  claim 3 , wherein
 the insulating sheet positioned between the cell case and the flat wound group has the holding portion. 
 
     
     
       5. The secondary cell according to  claim 4 , wherein
 the holding portion has a structure in which a plurality of insulating layers are superposed to form the insulating sheet. 
 
     
     
       6. The secondary cell according to  claim 3 , wherein
 the holding portion is formed to project from the cell case. 
 
     
     
       7. The secondary cell according to  claim 1 , wherein
 the holding portion is a holding portion held between a wide surface of the cell case near a cell case bottom and the flat wound group. 
 
     
     
       8. The secondary cell according to  claim 7 , wherein
 the holding portion is an insulating tape or a sheet-shaped member fixed to the flat wound group. 
 
     
     
       9. The secondary cell according to  claim 7 , wherein
 the holding portion is fixed to the cell case. 
 
     
     
       10. The secondary cell according to  claim 1 , wherein
 the secondary cell has a capturing/holding portion, and the flat wound group is held by a plurality of the holding portions and a plurality of the capturing/holding portions.